Feature: CLI flag to print all help command in tree hierarchy

[Arvindh]

Is your feature request related to a problem? Please describe.

No

Describe the feature you are requesting, as well as the possible use case(s) for it.

A CLI flag to print all help command in tree hierarchy , This will give overview of all available commands with CLI.
Some thing like below

$ build/cli --help-tree 
magistrala-cli: 
  bootstrap [create | get | update | remove | bootstrap | whitelist]: Bootstrap management
    bootstrap [<external_id> <external_key> | secure <external_id> <external_key> <crypto_key> ]: Bootstrap config
    create <JSON_config> <user_auth_token>: Create config
    get [all | <thing_id>] <user_auth_token>: Get config
    remove <thing_id> <user_auth_token>: Remove config
    update [config <JSON_config> | connection <id> <channel_ids> | certs  <id> <client_cert> <client_key> <ca> ] <user_auth_token>: Update config
    whitelist <JSON_config> <user_auth_token>: Whitelist config
  certs [issue | get | revoke ]: Certificates management
    get [<cert_serial> | thing <thing_id> ] <user_auth_token>: Get certificate
    issue <thing_id> <user_auth_token> [--ttl=8760h]: Issue certificate
    revoke <thing_id> <user_auth_token>: Revoke certificate
  channels [create | get | update | delete | connections | not-connected | assign | unassign | users | groups]: Channels management
    assign [users | groups]: Assign users or groups to a channel
      groups  <group_ids> <channel_id> <user_auth_token>: Assign groups
      users <relation> <user_ids> <channel_id> <user_auth_token>: Assign users
    connections <channel_id> <user_auth_token>: Connections list
    create <JSON_channel> <user_auth_token>: Create channel
    delete <channel_id> <user_auth_token>: Delete channel
    disable <channel_id> <user_auth_token>: Change channel status to disabled
    enable <channel_id> <user_auth_token>: Change channel status to enabled
    get [all | <channel_id>] <user_auth_token>: Get channel
    groups <channel_id> <user_auth_token>: List groups
    unassign [users | groups]: Unassign users or groups from a channel
      groups  <group_ids> <channel_id> <user_auth_token>: Unassign groups
      users <relation> <user_ids> <channel_id> <user_auth_token>: Unassign users
    update <channel_id> <JSON_string> <user_auth_token>: Update channel
    users <channel_id> <user_auth_token>: List users
  config <key> <value>: CLI local config
  domains [create | get | update | enable | disable | enable | users | assign | unassign]: Domains management
    assign [users]: Assign users to a domain
      users <relation> <user_ids> <domain_id> <token>: Assign users
    create <name> <alias> <token>: Create Domain
    disable <domain_id> <token>: Change domain status to disabled
    enable <domain_id> <token>: Change domain status to enabled
    get [all | <domain_id> ] <token>: Get Domains
    unassign [users]: Unassign users from a domain
      users <relation> <user_ids> <domain_id> <token>: Unassign users
    update <domain_id> <JSON_string> <user_auth_token>: Update domains
    users <domain_id>  <token>: List Domain users
  groups [create | get | update | delete | assign | unassign | users | channels ]: Groups management
    assign [users]: Assign users to a group
      users <relation> <user_ids> <group_id> <user_auth_token>: Assign users
    channels <group_id> <user_auth_token>: List channels
    create <JSON_group> <user_auth_token>: Create group
    delete <group_id> <user_auth_token>: Delete group
    disable <group_id> <user_auth_token>: Change group status to disabled
    enable <group_id> <user_auth_token>: Change group status to enabled
    get [all | children <group_id> | parents <group_id> | members <group_id> | <group_id>] <user_auth_token>: Get group
    unassign [users]: Unassign users from a group
      users <relation> <user_ids> <group_id> <user_auth_token>: Unassign users
    update <JSON_group> <user_auth_token>: Update group
    users <group_id> <user_auth_token>: List users
  health <service>: Health Check
  invitations [send | get | accept | delete]: Invitations management
    accept <domain_id> <user_auth_token>: Accept invitation
    delete <user_id> <domain_id> <user_auth_token>: Delete invitation
    get [all | <user_id> <domain_id> ] <user_auth_token>: Get invitations
    send <user_id> <domain_id> <relation> <user_auth_token>: Send invitation
  messages [send | read]: Send or read messages
    read <channel_id.subtopic> <user_token>: Read messages
    send <channel_id.subtopic> <JSON_string> <thing_key>: Send messages
  provision [things | channels | connect | test]: Provision things and channels from a config file
    channels <channels_file> <user_token>: Provision channels
    connect <connections_file> <user_token>: Provision connections
    test: test
    things <things_file> <user_token>: Provision things
  subscription [create | get | remove ]: Subscription management
    create <topic> <contact> <user_auth_token>: Create subscription
    get [all | <sub_id>] <user_auth_token>: Get subscription
    remove <sub_id> <user_auth_token>: Remove subscription
  things [create | get | update | delete | share | connect | disconnect | connections | not-connected | users ]: Things management
    connect <thing_id> <channel_id> <user_auth_token>: Connect thing
    connections <thing_id> <user_auth_token>: Connected list
    create <JSON_thing> <user_auth_token>: Create thing
    delete <thing_id> <user_auth_token>: Delete thing
    disable <thing_id> <user_auth_token>: Change thing status to disabled
    disconnect <thing_id> <channel_id> <user_auth_token>: Disconnect thing
    enable <thing_id> <user_auth_token>: Change thing status to enabled
    get [all | <thing_id>] <user_auth_token>: Get things
    identify <thing_key>: Identify thing
    share <thing_id> <user_id> <relation> <user_auth_token>: Share thing with a user
    unshare <thing_id> <user_id> <relation> <user_auth_token>: Unshare thing with a user
    update [<thing_id> <JSON_string> | tags <thing_id> <tags> | secret <thing_id> <secret> ] <user_auth_token>: Update thing
    users <thing_id> <user_auth_token>: List users
  users [create | get | update | token | password | enable | disable | channels | things | groups]: Users management
    channels <user_id> <user_auth_token>: List channels
    create <name> <username> <password> <user_auth_token>: Create user
    disable <user_id> <user_auth_token>: Change user status to disabled
    domains <user_id> <user_auth_token>: List domains
    enable <user_id> <user_auth_token>: Change user status to enabled
    get [all | <user_id> ] <user_auth_token>: Get users
    groups <user_id> <user_auth_token>: List groups
    password <old_password> <password> <user_auth_token>: Update password
    profile <user_auth_token>: Get user profile
    refreshtoken <token> [<domainID>]: Get token
    resetpassword <password> <confpass> <password_request_token>: Reset password
    resetpasswordrequest <email>: Send reset password request
    things <user_id> <user_auth_token>: List things
    token <username> <password> [<domainID>]: Get token
    update [<user_id> <JSON_string> | tags <user_id> <tags> | identity <user_id> <identity> ] <user_auth_token>: Update user

Indicate the importance of this feature to you.

Must-have

Anything else?

Implementation Idea:

package main

import (
	"fmt"
	"os"

	"github.com/spf13/cobra"
)

var rootCmd = &cobra.Command{
	Use:   "myapp",
	Short: "My application does amazing things",
}

var printTree bool

func main() {
	cobra.OnInitialize(initConfig)

	rootCmd.PersistentFlags().BoolVar(&printTree, "help-tree", false, "Print the command tree")

	// Add subcommands here
	rootCmd.AddCommand(cmd1)
	rootCmd.AddCommand(cmd2)
	rootCmd.AddCommand(cmd3)

	if printTree {
		printCommandTree(rootCmd, "")
		return
	}

	if err := rootCmd.Execute(); err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
}

func initConfig() {
	// Initialize configuration if needed
}

var cmd1 = &cobra.Command{
	Use:   "cmd1",
	Short: "Command 1",
	Run: func(cmd *cobra.Command, args []string) {
		fmt.Println("Command 1 executed")
	},
}

var cmd2 = &cobra.Command{
	Use:   "cmd2",
	Short: "Command 2",
	Run: func(cmd *cobra.Command, args []string) {
		fmt.Println("Command 2 executed")
	},
}

var cmd3 = &cobra.Command{
	Use:   "cmd3",
	Short: "Command 3",
	Run: func(cmd *cobra.Command, args []string) {
		fmt.Println("Command 3 executed")
	},
}

func printCommandTree(cmd *cobra.Command, indent string) {
	fmt.Println(indent + cmd.Use + ": " + cmd.Short)
	for _, c := range cmd.Commands() {
		printCommandTree(c, indent+"  ")
	}
}